What percentage of the cellular response to radiation is caused by direct effect?

The correct response is based on established radiobiology principles, which indicate that the direct effect of radiation accounts for a relatively small portion of the overall cellular response to radiation exposure. In general, the direct effect typically refers to the immediate damage caused by the radiation interacting directly with the DNA or other critical cellular components.

Research in radiobiology suggests that the direct effect contributes approximately 5-10% to the total biological effect of radiation on cells. Given this context, 5% is a commonly accepted estimate for the percentage of the cellular response attributed to direct effects of radiation. The majority of the cellular response is typically the result of indirect effects, which involve secondary reactions and the generation of free radicals that ultimately lead to cellular damage.

Therefore, since option B indicates 5%, it aligns with the accepted understanding of the low percentage of cellular responses attributed directly to the radiation itself, confirming its validity as the answer.